206 CHITONID^!. 



Poll called the animal Lophyrus, and he has given some 

 particulars of its anatomy. Neither Cuvier nor Leach 

 found any male organ in the individuals they examined ; 

 and little seems to be known of their sexual relations. 

 Their embryogeny, however, is no longer a mystery. In 

 the ' Transactions of the Royal Academy of Sciences at 

 Stockholm/ for 1855 will be found a most interesting ac- 

 count by Professor Loven of his observations on the de- 

 velopment of C. marginatus. He says that some indivi- 

 duals, kept in confinement, laid their eggs, loosely united 

 in clusters of from 7 to 16, upon small stones. Each egg 

 has a thick envelope. The embryo, which is exactly of 

 an oval shape, and without any trace of shell, is divided 

 by a circular indentation into two nearly equal parts. 

 The upper half is fringed with cirri, by means of which 

 the embryo swims ; and each side of the line of inden- 

 tation is furnished with a tuft of very fine filaments. 

 Close to this line on either side are perceptible two dark 

 points, which are the eyes. When freed from the egg, 

 the embryo assumes a more lengthened shape ; the lower 

 half soon afterwards exhibits transverse furrows and 

 joints, of which seven (besides the front lobe) are dis- 

 tinguishable ; and some granulations now make their 

 appearance as the first rudiments of the shell. The 

 animal bends itself frequently ; it is still quite soft, and 

 can only swim. Subsequently it begins to crawl. The 

 eyes are then more conspicuous; the joints become 

 separated, and acquire a shelly consistence; the cirri 

 and tufts disappear ; and the head is perfectly formed 

 with its membranous hood. The embryo at this stage 

 sometimes swims and sometimes crawls. The eyes are 

 placed on distinct protuberances, and consist of pigment- 

 spots and lenses ; and the foot is rather enlarged, 

 although some time elapses before this part attains its 



